Top 7 Supplements to Slow — or Reverse — Aging

NAD+ is a coenzyme found in every cell of your body. It powers DNA repair, fuels mitochondrial energy production, and activates sirtuins — the proteins David Sinclair calls "longevity genes." The problem: NAD+ declines by roughly half between youth and middle age.

NMN is a direct precursor to NAD+. Your body converts it inside cells, restoring levels that have declined with age. Dr. David Sinclair takes 1g of NMN per day and has done so publicly for years. A 2023 study in GeroScience confirmed NMN's efficacy and safety in healthy middle-aged adults.

Quality matters enormously here. Third-party testing has found many NMN products deliver significantly less than their label claims. Double Wood is consistently ranked among the highest-quality, most accurately-dosed options at a competitive price point.

Your mitochondria — the power plants of your cells — decline with age. They produce less energy and generate more cellular damage. The result: fatigue, muscle loss, and accelerated tissue aging. Urolithin A is the most compelling solution to emerge from mitochondrial biology in years.

It activates mitophagy — a process that selectively removes damaged mitochondria and triggers generation of fresh ones to replace them. In clinical trials, MitoPure demonstrated improved muscle endurance, mitochondrial function, and strength in older adults — without additional exercise. A 2025 RCT confirmed these effects.

Here's the catch: your body has to manufacture Urolithin A from ellagitannins in pomegranates and berries — but only 40% of people have the gut microbiome necessary to do this efficiently. Direct supplementation bypasses that variability entirely.

If you're going to start anywhere, Omega-3s have the strongest human evidence base of any supplement on this list. A landmark 2025 study in Nature Aging — 777 adults aged 70+ over three years — found that 1g of omega-3 daily slowed biological aging by approximately 3 months based on DNA methylation clocks.

When combined with Vitamin D and exercise, the effects were additive: the combination cut pre-frailty risk by 39% and invasive cancer risk by 61%. Omega-3 alone reduced infections by 13% and falls by 10%.

Peter Attia has consistently included omega-3s in his stack, targeting 2–4g EPA+DHA daily based on bloodwork, monitoring his omega-3 index to keep it in the optimal 10–12% range.

Every day, some of your cells reach the end of their useful life. Normal cells self-destruct in an orderly process. But some — called senescent cells — refuse to die. They don't divide. They don't contribute. They just linger, pumping out inflammatory signals that damage neighboring healthy cells and drive virtually every major age-related disease.

These are what the longevity community calls zombie cells. And clearing them out is one of the most exciting frontiers in aging science.

Fisetin is a plant flavonoid that functions as a senolytic — selectively targeting and eliminating senescent cells while leaving healthy cells intact. David Sinclair takes 500mg of fisetin daily. Bryan Johnson includes senolytics in his protocol.

Spermidine is a naturally occurring polyamine found in wheat germ, aged cheese, mushrooms, and soybeans. Its primary mechanism: it's one of the most potent natural activators of autophagy — the cellular self-cleaning process where damaged cellular components are broken down and recycled.

Think of autophagy as your cells' internal cleanup crew. As you age, that crew gets lazy. Spermidine helps wake it back up. Epidemiological data shows that higher dietary spermidine intake correlates with reduced all-cause mortality across populations.

David Sinclair includes spermidine in his stack specifically to "induce autophagy," complementing the autophagy-enhancing effects of intermittent fasting. Peter Diamandis also includes it in his daily supplement stack.

This might seem basic compared to the more exotic compounds on this list. Don't let that fool you. Vitamin D deficiency is epidemic — most adults in modern societies spend most of their time indoors and don't get close to adequate Vitamin D from sunlight or diet.

A 2025 analysis of the VITAL trial — 25,000 adults over five years — found that 2,000 IU of Vitamin D3 daily slowed telomere shortening by ~140 base pairs over four years. Researchers estimate this equals roughly 3 years of cellular aging prevented — the most powerful single anti-aging effect documented for any standalone supplement in a large human trial.

Why K2 matters: Vitamin D increases calcium absorption — good for bones, potentially dangerous if that calcium ends up in your arteries. K2 (MK-7) acts as a calcium traffic director, sending it to bones and away from arterial walls. Peter Attia takes up to 5,000 IU/day calibrated to bloodwork.